Revert of "Update Dr. Memory to 1.8.16559 (0xb9c673b). This re-lands fixes for problems handling HeapWalk(). This also fixes https://github.com/DynamoRIO/dynamorio/issues/1690, https://github.com/DynamoRIO/drmemory/issues/1718, and https://github.com/DynamoRIO/drmemory/issues/1722."
Reason for revert: while it fixed some issues it introduced more.
This reverts commit
5ffa0d05e37bfc565a68ad949c780c15c040d902.
BUG=481231
TBR=thestig@chromium.org
NOTRY=true
Review URL: https://codereview.chromium.org/
1125683003
Cr-Commit-Position: refs/heads/master@{#328127}